Epicotyl and Hypocotyl Germination of Eastern Redcedar and Rocky Mountain Juniper
Approximately 200 seeds each of eastern redcedar (Juniperus virginiana L.) and Rocky Mountain juniper (J. scopulorum Sarg.) were subjected to different pregermination treatments. Cutting seed bases (hilum) resulted in epicotyl development (abnormal germination) within 3 to 9 days. Sulfuric acid treatments of 35-minutes for J. virginiana and 120 minutes for J. scopulorum produced a hole in the hilum and resulted in similar types of germination. The diameter of the hilum hole was 3 to 6 times larger in J. virginiana than in J. scopulorum. Chilling was necessary to break hypocotyl dormancy. The vascular tissue of the fruit base which covers the hilum resisted sulfuric acid. This tissue prohibits moisture absorption and explains delayed germination of seeds planted with intact fruits. Epicotyl germination resulted in normal seedlings, and cutting epicotyl above the female gametophyte culminated in rooting within 3 to 4 weeks in a nutrient solution. J. scopulorum seeds were germinated normally within 4 months, half the previously reported periods, following sulfuric acid treatment. Carbonized surface of seeds from sulfuric acid treatment prohibited seed germination, possibly due to interference with respiration and subsequent seed degeneration. The results of this study show that slow germination of juniper seeds results from a combination of chemical factors in the embryo and physical factors in the seedcoat. Forest Sci. 22:261-266.
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